The present invention relates to a seedling-growing sheet adapted for growing seedlings of, for example, paddy rice, a method of manufacturing the same, a planting device used in planting the seedling-growing sheet, and a planting machine equipped with said planting device.
A method of growing seedlings from rice seeds and planting the grown seedlings in a paddy field is disclosed in Japanese Patent Disclosure (Kokai) No. 50-57808. In this prior art, an assembly prepared by mutually bonding a large number of paper cylinders on a single plane is used for growing seedlings. Each paper cylinder is loaded with soil, and a rice seed is sown in the soil loaded in each paper cylinder so as to grow the seedlings of the paddy rice. After growth of the seedlings, the paper cylinders are individually separated from each other, and the separated paper cylinder housing the grown rice seedling is planted manually or by a planting machine in a paddy field.
In the prior art described above, however, a large area is required for growing the seedlings because a large number of paper cylinders are arranged side by side on a single plane. Naturally, it is laborious to handle the assembly of the paper cylinders. In addition, since soil is loaded in each paper cylinder, each paper cylinder is so heavy that it is highly laborious to transfer the assembly of the paper cylinders. Also, the soil tends to be scattered about in loading the soil in the paper cylinder so as to stain the working environment.
What should also be noted is that, when the paper cylinders housing the rice seedlings are planted in a paddy field by using a planting machine, it is necessary to regulate highly accurately the positional relationship between the planting machine and the paper cylinders, making it necessary to define strictly the relative positions of the paper cylinders arranged on a single plane. It follows that it is highly laborious to prepare the assembly of the paper cylinders so as to inhibit the mass production of the rice seedlings.
A first object of the present invention is to provide a seedling-growing sheet that permits growing seedlings without using soil so as to make the seedling-growing sheet small in size and light in weight and also permits easily mass production of seedlings.
A second object of the present invention is to provide a method of manufacturing a seedling-growing sheet of a laminate structure comprising receptacles of seeds and seedlings grown from the seeds and cutting perforations along which a planting piece including a receptacle is cut away from the seedling-growing sheet.
Further, a third object of the present invention is to provide a planting device that permits cutting away a planting piece from the seedling-growing sheet easily and without fail and also permits planting the planting pieces continuously in the field, and to provide a planting machine provided with the particular planting device.
The first object of the present invention can be achieved by a seedling-growing sheet, comprising:
a laminate body including a band-like support member and a porous sheet body laminated on the support member;
a large number of receptacles for housing seeds and seedlings grown from the seeds, the receptacles being formed in the sheet body of the laminate body and arranged apart from each other in the longitudinal direction of the support member; and
cutting perforations consisting of a large number of cut lines, the cutting perforations extending across the width of the laminate body and arranged a predetermined distance apart from each other in the longitudinal direction of the laminate body to have a planting piece including at least one receptacle defined between two adjacent cutting perforations.
According to the seedling-growing sheet of the construction described above, the seedling is grown with the seed housed in the receptacle of the sheet body, making it unnecessary to use soil for growing the seedling. Therefore, the seedling can be grown under a clean environment. In addition, the seedling-growing sheet itself can be made small in size and light in weight so as to facilitate the handling such as transference of the seedling-growing sheet.
Also, since cutting perforations are formed in the seedling-growing sheet, the planting piece defined between adjacent cutting perforations can be cut away easily from the seedling-growing sheet along the cutting perforation. Naturally, it is possible to prevent the planting piece from being partially broken and to prevent a plurality of planting pieces from being cut away together when the planting pieces are planted in the field. It follows that the seedlings can be planted continuously in the field.
In addition, a large number of receptacles are formed a predetermined distance apart from each other in the longitudinal direction of the seedling-growing sheet, making it possible to grow a large number of seedlings in a single seedling-growing sheet. What should also be noted is that the seedling-growing sheet is in the form of a band, making it possible to wind the sheet to form a sheet roll in the step of growing the seedlings. In this case, it is possible to send out easily the seedling-growing sheet from the sheet roll in the longitudinal direction of the sheet so as to avoid troubles in the step of sending out the seedling-growing sheet.
The second object of the present invention can be achieved by a method of manufacturing a seedling-growing sheet, comprising:
a first step of forming a large block consisting of a porous material;
a second step of slicing the large block to form a band-like sheet body having an optional thickness;
a third step of forming a laminate body by laminating the band-like sheet body on a band-like support member; and
a fourth step of forming a large number of receptacles for housing seeds in the sheet body of the laminate body a predetermined distance apart from each other in the longitudinal direction of the laminate body and a large number of cutting perforations extending across the width of the laminate body and arranged a predetermined distance apart from each other in the longitudinal direction of the laminate body to have a planting piece including at least one receptacle defined between two adjacent cutting perforations.
The particular method of the present invention makes it possible to arrange the first to fourth manufacturing steps on a continuous single line to manufacture efficiently a laminate body having receptacles and cutting perforations.
The third object of the present invention can also be achieved by a planting device, comprising:
a sheet holding section for holding a seedling-growing sheet including a band-like body, a large number of receptacles for housing seeds, which are formed a predetermined distance apart from each other in the longitudinal direction of the band-like body, and a large number of cutting perforations extending across the width of the band-like body and arranged a predetermined distance apart from each other in the longitudinal direction of the band-like body to have a planting piece including at least one receptacle defined between two adjacent cutting perforations;
a transfer mechanism for sending out the seedling-growing sheet from the sheet holding section;
a planting mechanism equipped with a planting claw movable substantially in a vertical direction, the planting claw of the planting mechanism being engaged with a tip portion of the seedling-growing sheet sent out from the sheet holding section to permit the planting piece to be cut away from the seedling-growing sheet along the cutting perforation and to be planted in a field; and
a sheet-fixing mechanism arranged contiguous to the engaging section between the seedling-growing sheet and the planting claw so as to fix the seedling-growing sheet when the planting piece is cut away by the planting claw from the seedling-growing sheet.
The third object of the present invention can also be achieved by a planting machine, comprising:
a running vehicle provided with wheels;
a sheet-holding section mounted to a rear portion of the running vehicle;
a seedling-growing sheet mounted to the sheet-holding section and including a band-like body, a large number of receptacles for housing seeds, which are formed a predetermined distance apart from each other in the longitudinal direction of the band-like body, and a large number of cutting perforations extending across the width of the band-like body and arranged a predetermined distance apart from each other in the longitudinal direction of the band-like body to have a planting piece including at least one receptacle defined between two adjacent cutting perforations;
a transfer mechanism for sending out the seedling-growing sheet from the sheet holding section;
a planting mechanism equipped with a planting claw movable substantially in a vertical direction, the planting claw of the planting mechanism being engaged with a tip portion of the seedling-growing sheet sent out from the sheet holding section to permit the planting piece to be cut away from the seedling-growing sheet along the cutting perforation and to be planted in a field; and
a sheet-fixing mechanism arranged contiguous to the engaging section between the seedling-growing sheet and the planting claw so as to fix the seedling-growing sheet when the planting piece is cut away by the planting claw from the seedling-growing sheet.
In the planting machine of the particular construction, the seedling-growing sheet is sent out by the transfer mechanism from the sheet-holding section. When the planting claw of the planting mechanism is engaged with a tip portion of the seedling-growing sheet, the planting piece is cut away from the seedling-growing sheet along the cutting perforation. When the planting piece is cut away from the seedling-growing sheet, the remaining seedling-growing sheet is fixed by the sheet-fixing mechanism. As a result, the seedling-growing sheet is prevent from being bent when the planting piece is cut away from the sheet, making it possible to cut away the planting pieces one by one along the cutting perforations easily and without fail. It follows that the planting piece is prevented from being broken partially and a plurality of planting pieces are prevented from being cut away simultaneously. Naturally, the planting pieces can be planted in the field continuously, leading to an efficient seedling-planting operation.
The support member included in the seedling-growing sheet of the present invention is formed of, for example, a film of thermoplastic resins such as polyethylene, polypropylene, acrylic resin and polyurethane; a film of thermosetting resin such as polyester; and a cellulose sheet such as woven or unwoven fabric and a paper sheet.
It is desirable for the support member to be biodegradable because the planting piece including the support member is left buried in the field after the planting step of the planting piece. The support member, which is biodegradable, is naturally decomposed biologically within the field so as to prevent contamination of the soil.
The biodegradable support members include types (1) to (3) given below:
(1) Known biodegradable resin films including those using natural polymers based on polysaccharides such as starch, cellulose and chitin as base materials; those using as base materials mixtures prepared by adding biodegradable resins such as starch and decomposition-promoting additives to general purpose plastic materials such as polyethylene and polystyrene; and those using as base materials polylactic acid, polymalic acid and polycaprolactam;
(2) Woven and unwoven fabrics using natural fibers; and
(3) A cellulose sheet such as Japanese paper and machine-made paper.
It is desirable to determine the thickness of the support member not to obstruct the seedling-growing and seedling-planting operations. In the case of using, for example, the biodegradable resin film of type (1) given above, the thickness of the resin film should be 0.05 to 0.15 mm, desirably about 0.12 mm.
In the case of using the unwoven fabric of type (2) given above, it is desirable to set the basis weight of the sheet at 20 to 80 g/m2 and the thickness of the sheet at 0.15 to 0.8 mm, preferably 0.2 to 0.4 mm. Also, in the case of using a woven fabric of a natural fiber, it is desirable to apply processing to the woven fabric depending on the density of the natural fiber.
The porous sheet body included in the laminate body of the present invention includes, for example, a soft or semirigid polyurethane foam sheet and an unwoven fabric. The sheet body should be thick enough to house the entire seed, e.g., 3 mm to 10 mm, preferably about 3 mm to 5 mm.
It is desirable for the polyurethane foam sheet to be biodegradable like the support member in order to prevent the soil of the field from being contaminated. The polyurethane foam sheet can be made biodegradable by allowing the foam sheet to contain, for example, polysaccharide series waste materials of agricultural products such as starch represented by corn, wheat and potato, molasses (refined molasses), soybean cakes, and skins of oranges.
The term xe2x80x9cseedxe2x80x9d used herein includes the seed after germination.